1. Field of the Invention
This invention relates to a regenerative heat exchanger having particular utility in providing fresh air ventilation without loss of heat or cooling for residential, commercial, and office buildings. The heat exchanger of the invention is compact in size, low in initial cost, and provides high efficiency.
The basic heat transfer mechanism of the apparatus of the invention involves the passage of a gas stream at a given temperature through a plurality of spaced beds of confined, randomly packed metal particles for a predetermined period of time, followed by a second gas stream flowing in the opposite direction through the beds at a different temperature for a similar period of time. Thereafter, the process is repeated continuously, except for the brief period of time during which the gas flows are reversed.
2. The Prior Art Regenerative heat transfer is well known and has many applications, including ventilation of residential, commercial, and office buildings.
The metal particles which are the preferred heat exchange medium in the apparatus of the invention are flakes produced by a known process of rapid solidification applicable to many metals, and currently in use for production of large quantities of aluminum flakes, each flake having a thickness of about 0.03 to about 0.04 mm, and a length and width ranging from about 1.0 to about 1.7 mm. This aluminum flake product is relatively inexpensive.
U.S. Pat. No. 3,233,659, issued Feb. 8, 1966, to F. Nettel et al., discloses cup-shaped pellets of thin-walled metal as a heat exchange medium falling in counterflow to a rising gas stream. The pellets are preferably made of thin stainless or other alloy steel. Mention is made of aluminum or magnesium pellets, but the use thereof is stated to be restricted.
U.S. Pat. No. 4,218,290, issued Aug. 19, 1980, to J. R. Phillips et al., discloses the use of pellets of iron, stainless steel, or aluminum of a particle size of about 1/8 to 1/2 inch, in a system for recovery of potable water from saline solutions. A multiplicity of beds is used to heat the saline solution, and a multiplicity of beds is used to condense water while a bed is heated for service.
U.S. Pat. No. 4,349,069, issued Sept. 14, 1982, to H. F. von Beck, discloses a gas-to-gas regenerative heat exchanger having an undefined mass of heat absorbent material. The apparatus includes a housing, a hot end of the heat exchanger having an inlet duct for a heating fluid and an outlet duct for heated air, and a cold end having an outlet duct for cooled fluid and an inlet duct for cool air. Valve means are provided in the inlet and outlet ducts to control the flow of fluid and/or gas therethrough.
Other patents relating to regenerative gas-to-gas heat exchangers include U.S. Pat. No. 2,891,774, issued June 23, 1959, to Theoclitus, U.S. Pat. No. 3,039,745, issued June 19, 1962 to M. K. Drewry; U.S. Pat. No. Re. 17,577 issued Feb. 4, 1930, to W. Dyrssen; and U.S. Pat. No. 1,688,700, issued Oct. 23, 1928, to H. F. Gauss.
Despite the continued development of regenerative heat exchangers over a relatively long period of time, there is still a genuine need for a relatively compact, inexpensive air-to-air regenerative heat exchanger capable of providing fresh air ventilation without loss of heat or cooling, which is highly cost effective in operation.
It is a primary objective of the present invention to provide a regenerative gas-to-gas heat exchanger which fulfills the above need.